Color hologram display and its fabrication process

ABSTRACT

The invention relates to a color hologram display an image of a three-dimensional object and a hologram image of a pattern of plane characters, images or the like are recorded in the same volume type hologram photosensitive material in a superposed or multiplexed fashion. A color hologram display  27′  comprising a combined reflection and volume type of single layer, wherein a color pattern  29   g  of plane characters, images or the like and a color three-dimensional subject image O″ are reconstructably recorded while spatially superposed one upon another.

This application is a continuation of U.S. patent application Ser. No.09/547,663, filed Apr. 12, 2000.

BACKGROUND OF THE INVENTION

The present invention relates generally to a color hologram display andits fabrication process, and more particularly to a color hologramdisplay wherein a plane pattern such as a plane character or imagepattern is superposed and recorded as a hologram on a full-colorLippmann hologram using a three-dimensional object as a subject and itsfabrication process.

Never until now is there an entrenched process for incorporating ahologram form of characters, images, etc. in a full-color Lippmannhologram using a three-dimensional model or the like as athree-dimensional subject.

SUMMARY OF THE INVENTION

In view of such situations as experienced in the prior art, an object ofthe present invention is to provide a color hologram display wherein animage of a three-dimensional object such as a three-dimensional modeland a hologram image of a plane pattern such as a character or imagepattern are recorded in the same volume hologram photosensitive materialin a superposed or multiplexed fashion, and its fabrication process.

According to the present invention, this object is achieved by theprovision of a color hologram display comprising a combined reflectionand volume type of single layer, wherein a color pattern of planecharacters, images or the like and a color three-dimensional subjectimage are reconstructably recorded while spatially superposed one uponanother.

Preferably in this case, the plane color pattern of characters, imagesor the like is reconstructably recorded in monochrome. In view ofviewability, the plane color pattern should be reconstructably recordedin green.

Preferably, the plane shadow of the color pattern of plane characters,images or the like should be reconstructably recorded on a surfacedifferent from a surface of the color pattern.

Preferably, the shadow should be reconstructably recorded in acomplementary color to a color of the color pattern.

Preferably, the shadow should be reconstructably recorded in front ofthe color pattern.

Preferably, any shadow of the color pattern of plane characters, imagesor the like should be unrecorded.

The present invention provides a process of fabricating a color hologramdisplay, wherein a color three-dimensional subject image and a colorpattern of plane characters, images or the like are recorded as hologramimages in the same photosensitive material.

Preferably in this case, a subject hologram plate for forming a colorthree-dimensional subject image and a character hologram plate forreconstructing the color pattern of plane characters, images or the likeare separately made, said subject hologram plate and said characterhologram plate are spatially positioned with a given space locatedtherebetween, and diffracted light from said subject hologram plate andsaid character hologram plate is simultaneously entered in the samephotosensitive material to record said subject and character hologramplates as hologram images.

Preferably, an area of said hologram photosensitive material other thana portion thereof corresponding to said color pattern of planecharacters, images or the like is deactivated by photosensitization, anda reflection type hologram of a scatter plate is then recorded in saidportion of said hologram photosensitive material to make said hologramplate.

Preferably, said subject hologram plate is recorded in three colors,red, green and blue and said character hologram plate is recorded in anyone of red, green and blue. More preferably, said character hologramplate is recorded in green.

Preferably, said character hologram plate for reconstructing said colorpattern of plane characters, images or the like is made, said characterhologram plate is located in front of a color three-dimensional subject,and diffracted light from said character hologram plate and scatteredlight from said color three-dimensional subject are simultaneouslyentered in the same photosensitive material to record said hologramplates as hologram images.

Preferably, a subject hologram plate for forming a colorthree-dimensional subject image and a character hologram plate forreconstructing a color pattern image of plane characters, images or thelike are separately made, said subject hologram plate and said characterhologram plate are superposed one upon another, and diffracted lightfrom said subject hologram plate and said character hologram plate issimultaneously entered in the same photosensitive material to recordsaid color three-dimensional subject image and said color pattern imageof plane characters, images or the like as hologram images.

The present invention includes a subject hologram plate used tofabricate a color hologram display wherein a subject hologram plate forforming a color three-dimensional subject image and a character hologramplate for reconstructing a color pattern image of plane characters,images or the like are separately made, said subject hologram plate andsaid character hologram plate are positioned with a given space locatedtherebetween, and diffracted light from said subject hologram plate andsaid character hologram plate is simultaneously entered in the samephotosensitive material to record said color three-dimensional subjectimage and said color pattern image of plane characters, images or thelike as hologram images.

The present invention also includes a subject hologram plate used tofabricate a color hologram display wherein a subject hologram plate forforming a color three-dimensional subject image and a character hologramplate for reconstructing a color pattern image of plane characters,images or the like are separately made, said subject hologram plate andsaid character hologram plate are superposed one upon another, anddiffracted light from said subject hologram plate and said characterhologram plate is simultaneously entered in the same photosensitivematerial to record said color three-dimensional subject image and saidcolor pattern image of plane characters, images or the like as hologramimages.

According to the present invention, the color pattern of planecharacters, images or the like and the color image of athree-dimensional subject can be reconstructably recorded withoutcrosstalk and unnecessary interference fringes, while they are spatiallysuperposed one upon another. It is thus possible to obtain a colorhologram display which enables a bright color subject image and ablur-free, bright color pattern having visibility to be displayed at thesame time, and is of great versatility as well. According to the presentinvention, even when a color pattern of characters, images, etc. isreconstructably incorporated in the hologram for reconstructing thecolor image of a three-dimensional subject, a bright subject image canbe obtained with the same efficiency as that of a pattern-free hologram.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrative of one character hologram platefabrication step used for the fabrication of the color hologram displayaccording to the present invention.

FIG. 2 is a view illustrative of the step of making a reflection typehologram scatter plate used for the character hologram plate fabricationstep.

FIG. 3 is a view illustrative of the final step of making the characterhologram plate.

FIG. 4 is a view illustrative of the characteristics of the characterhologram plate.

FIG. 5 is a view illustrative of the step of making a subject hologramplate used for the fabrication of the color hologram display accordingto the present invention.

FIG. 6 is a view illustrative of the step of fabricating using both thecharacter hologram plate and the subject hologram for the fabrication ofthe color hologram display according to the present invention.

FIG. 7 is a view illustrative of how to reconstruct the image of athree-dimensional subject recorded in the color hologram displayaccording to the present invention.

FIG. 8 is a view illustrative of how to fabricate the color hologramdisplay of the present invention directly from the character hologramplate and three-dimensional subject.

FIG. 9 is a view illustrative of the final step of making the characterhologram plate used for the fabrication of a shadow-free color hologramdisplay according to the present invention.

FIG. 10 is a view illustrative of the step of fabricating theshadow-free color hologram display according to the present inventionusing the character hologram of FIG. 9 and the subject hologram of FIG.5.

FIG. 11 is a view illustrative of reconstructing the image of thethree-dimensional subject recorded in the shadow-free color hologramdisplay according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The color hologram display according to the present invention is nowexplained with reference to its fabrication process.

To fabricate a color hologram display 27′ (FIG. 7) according to thepresent invention, a character hologram plate 1′ (FIG. 4) and a subjecthologram plate 21′ (FIG. 6) must be prepared.

How to prepare the character hologram plate 1′ is first explained. Asshown in FIG. 1, a volume hologram photosensitive material 1 such as aphotopolymer is first provided as a hologram photosensitive material.Then, a character or image pattern to be displayed on the photosensitivematerial 1 in a superposed or multiplexed fashion, for instance, acharacter pattern plate 2 comprising an opaque “ABC” pattern portion 2 aand its transparent peripheral portion is placed on the photosensitivematerial 1, which is then irradiated with light 3 such as ultravioletlight from the character pattern plate 2 side. With the volume hologramphotosensitive material 1 irradiated with light 3 through the characterpattern plate 2, an area of the photosensitive material 1 other than aportion (1 a in FIG. 3) thereof corresponding to the pattern portion 2 aremains inert while only the portion 1 a corresponding to the patternportion 2 a provides an activated area.

As shown in FIG. 2, on the other hand, a separately provided volumehologram photosensitive material 5 is superposed on a scatter plate 4such as a ground or opal glass plate. Then, green (G) reference light 6g for instance is entered at a given angle θ of incidence in the volumehologram photosensitive material 5 and, at the same time, greenillumination light 7 g is entered in the back surface of the scatterplate 4, so that object light transmitted and scattered through thescatter plate 4 and reference light 6 g interfere in the volume hologramphotosensitive material 5. A reflection type hologram scatter plate 5′(FIG. 3) is thus prepared.

Then, as shown in FIG. 3, the volume hologram photosensitive material 1,whose portion other than the character pattern-corresponding portion 1 aremains deactivated as shown in FIG. 1, is superposed on the thusprepared reflection type hologram scatter plate 5′. As the volumehologram photosensitive material 1 is irradiated at a given angle ofincidence with illumination light 8 g having the same wavelength as thereference light 6 g used to make the reflection type hologram scatterplate 5′, the illumination light 8 g transmits through the volumehologram photosensitive material 1 and strikes on the reflection typehologram scatter plate 5′ to diffract scattered light 9 g in thedirection of reflection. The scattered light 9 g and incident light 8 ginterfere in the activated character pattern-corresponding portion 1 aof the volume hologram photosensitive material 1, so that a reflective,scattering hologram can be recorded in the characterpattern-corresponding portion 1 a.

The thus recorded character hologram plate 1′ is a reflection typehologram which diffracts green scattered light 11 g from only a portion1′a corresponding to the pattern portion 2 a of the character patternplate 2 in the direction of reflection upon illuminated at around anangle of incidence θ with white light 10 w including a green wavelength.In this embodiment, the characters “ABC” can be seen in green.

According to the above embodiment, the character hologram plate 1′ mayalso be made by using a reflection or transmission type scatter plate inplace of the reflection type hologram scatter plate 5′. The reflectiontype scatter plate may be located at the position of the reflection typehologram scatter plate 5′ shown in FIG. 3. The transmission type scatterplate may be located at the position of the reflection type hologramscatter plate 5′ as shown in FIG. 3 and, at the same time, irradiatedwith illumination light from behind.

Next, how to make the subject hologram plate 21′ is explained. As shownin FIG. 5, a volume hologram photosensitive material 21 is located awayfrom a three-dimensional subject O such as a three-dimensional model. Inthis case, a volume hologram photosensitive material having sensitivitywith respect to three colors, red, green and blue and capable ofmultiplex recording is used as the volume hologram photosensitivematerial 21. However, it is acceptable to use a volume hologramphotosensitive material of three-layer construction whereinphotosensitive layers sensitive to red, green and blue, respectively,are laminated one upon another. Alternatively, it is acceptable tosuperpose separately exposed color photosensitive layers.

In such a setting, red light, green light and blue light in the form ofillumination light 22 rgb are entered at an angle of incidence θ in thevolume hologram photosensitive material 21 side at the same time or inarbitrary order. Thereupon, the illumination light 22 rgb transmitsthrough the volume hologram photosensitive material 21 and strikes onthe three-dimensional subject O, from which scattered light 23 rgb isproduced in the direction of reflection. The scattered light 23 rgb andillumination light 22 rgb interfere in the volume hologramphotosensitive material 21, so that a reflection type hologram 21′ ofthe three-dimensional subject O can be recorded in full color (see FIG.6). This reflection type hologram 21′ is used as the subject hologramplate 21′.

Using this subject hologram plate 21′ and the character hologram plate1′ of FIG. 4, a color hologram display 27′ (see FIG. 7) is fabricated,which reconstructs a character pattern such as a “ABC” pattern in theforeground of a hologram reconstructed image O″ of the three-dimensionalsubject O. To this end, as shown in FIG. 6, another volume hologramphotosensitive material 27 is located in the vicinity of thethree-dimensional subject O used for recording the subject hologramplate 21′ while the character hologram plate 1′ is located at a positionthat is between the subject hologram plate 21′ and the volume hologramphotosensitive material 27 and that is in front of the position of thethree-dimensional subject O located during recording (on the subjecthologram plate 21′ side) and as close to the volume hologramphotosensitive material 27 as possible. In this condition, red light,green light and blue light in the form of illumination light 24 rgb areallowed to strike simultaneously or in arbitrary order on the volumehologram photosensitive material 27 from the opposite direction to thedirection of incidence of the illumination light 22 rgb used to make thesubject hologram plate 21′. Then, the illumination light 24 rgbtransmits through the volume hologram photosensitive material 27 andstrikes on the character hologram plate 1′, so that green scatteredlight 11 g is diffracted from the character pattern portion such as a“ABC” pattern portion 1′a (see FIG. 4) in the direction of reflection.The scattered light 11 g and the green component of illumination light24 rgb interfere in the volume hologram photosensitive material 27 sothat the character “ABC” pattern can be recorded in the form of areflection type hologram.

The illumination light 24 rgb transmits through the volume hologramphotosensitive material 27 and the character hologram plate 1′ andenters the subject hologram plate 21′, where the light 24 rgb isdiffracted in the direction of reflection to reconstruct the real imageO′ of the recorded three-dimensional subject O in the vicinity of thesurface of the volume hologram photosensitive material 27. Thisdiffracted light and illumination light 24 rgb interfere in the volumehologram photosensitive material 27, so that the hologram image of thethree-dimensional subject O can be recorded therein.

Accordingly, the character “ABC” pattern 1′a of the character hologramplate 1′ and the image O′ of the three-dimensional subject O arerecorded as a reflection type hologram in the volume hologramphotosensitive material 27 while they are kept in the position relationshown in FIG. 6.

It is here noted that when color hologram recording is carried out insuch a setting, one pseudoscopic image is recorded. This pseudoscopicimage (shadow) is now explained. In FIG. 6, consider that theillumination light 24 rgb strikes on the pattern portion 1′a of thecharacter hologram plate 1′. The hologram recorded in that portioncauses the green component (in the above embodiment) to be diffracted asthe scattered light 11 g in the direction of reflection. For thisreason, light (component) 25 rb that transmits through the patternportion 1′a of the character hologram plate 1′ without undergoingdiffraction is given by the red and blue components of the illuminationlight 24 rgb. It is here understood that when the diffraction efficiencyof the hologram recorded in the pattern portion 1′a is lower than 100%,the light component 25 rb partially contains the green component.Accordingly, the red and blue components are mainly diffracted from anarea 26 where the transmitted light 25 rb enters the subject hologramplate 21′; that is, the light 25 rb contains a small amount of the greencomponent to be originally diffracted. As a result, the area 26corresponding to the shadow of the pattern portion 1′a of the characterhologram plate 1′ on the subject hologram plate 21′ is recorded as apseudoscopic image in the volume hologram photosensitive material 27.The shadow corresponding to the area 26 is recorded as a reflection typehologram while the character “ABC” pattern 1′a of the character hologramplate 1′ and the image O′ of the three-dimensional subject O are kept inthe position relation shown in FIG. 6. The image O′ is recorded inmagenta that is a complementary color to green, i.e., white from whichthe green component is subtracted.

As mentioned above, the color hologram display 27′ is recorded in such amanner that the character pattern, for instance, a character “ABC”pattern 29 g is reconstructed in the foreground of the hologramreproduced image O″ of the three-dimensional subject O. As shown in FIG.7, white illumination light 28 w enters the color hologram display 27′from the direction opposite to the direction of incidence of theillumination light 24 rgb used to record the display 27′, whereupondiffracted light reconstructs the color image O″ of thethree-dimensional subject O in the vicinity of the surface of the colorhologram display 27′. At the same time, in front of the color image O″the plane characters “ABC” 29 g corresponding to the pattern portion 2 aof the character pattern plate 2 are reconstructed in green and in frontthereof the plane, magenta shadow 30 m of the characters “ABC” isreconstructed. Accordingly, when the observer views the color hologramdisplay 27′ through his eyes E, he sees the image 29 g of the plane,green characters “ABC” just in front of the color image O″ of thethree-dimensional subject O, as if they were superposed one uponanother, and the shadow 30 m of the plane, magenta characters “ABC” justin front thereof. When the observer moves his eyes E to the left, thecharacter image 29 g and shadow 30 m move to the right with respect tothe subject image O″ so that he can see them in a superposed manner whenthe direction of observation with his eyes E coincide with the directionof the illumination light 28 w. At otherwise positions, the characterimage 29 g and its shadow 30 m do not align with each other not only inperspective but in the horizontal direction as well.

The above embodiment is directed to the process of producing the colorhologram display 27′ of the present invention using the characterhologram plate 1′ (FIG. 4) and the subject hologram plate 21′ (FIG. 6).However, the color hologram display of the present invention may beproduced more easily as explained with reference to FIG. 8. As shown inFIG. 8, another volume hologram photosensitive material 31 is located infront of a three-dimensional subject O, and the character hologram plate1′ of FIG. 4 is placed between the volume hologram photosensitivematerial 31 and the three-dimensional subject O. In this condition, redlight, green light and blue light in the form of illumination light 24rgb strike simultaneously or in arbitrary order on the volume hologramphotosensitive material 31 from the opposite direction to the directionof incidence of the illumination light 8 g used to make the characterhologram plate 1′. Then, the illumination light 24 rgb transmits throughthe volume hologram photosensitive material 31 and enters the characterhologram plate 1′, so that green scattered light 11 g is diffracted fromthe character pattern portion such as a “ABC” pattern portion 1′a (seeFIG. 4) in the direction of reflection. The scattered light 11 g and thegreen component of illumination light 24 rgb interfere in the volumehologram photosensitive material 31 so that the character “ABC” patterncan be recorded in the form of a reflection type hologram. At the sametime, the illumination light 24 rgb transmitting through the volumehologram photosensitive material 31 enters the three-dimensional subjectO, so that scattered light 23 rgb is produced from the subject O in thedirection of reflection. This scattered light 23 rgb and theillumination light 24 rgb interfere in the volume hologramphotosensitive material 32, so that the full-color reflection typehologram of the three-dimensional subject O can be recorded in amultiplex fashion. The thus recorded color hologram display is differentfrom the color hologram display 27′ of FIG. 7 in that the shadow of thecharacter pattern portion 1′a of the character hologram plate 1′ isdirectly formed as an area 32 on the three-dimensional subject O. Uponreconstruction, this image is formed as a magenta shadow on the surfaceof the image of the three-dimensional subject O, and therefore the imageof the shadow is not recorded in the form of a three-dimensionalpseudoscopic image.

In the embodiments explained above, the shadow of the character patternportion 1′a of the character hologram plate 1′ is formedthree-dimensionally in the space or on the surface side of the hologramreproduced image O″ of the three-dimensional subject O. In what follows,one embodiment of fabricating a color hologram display which, withoutforming such a shadow, reconstructs characters, etc. in the foregroundof the hologram reproduced image O″ of the three-dimensional subject O.

To fabricate a color hologram display 44′ (FIG. 11) according to thisembodiment, a character hologram plate 41′ (FIG. 4) and a subjecthologram plate 21′ (FIG. 10) must be prepared.

How to prepare the character hologram plate 41′ is first explained. Thesame steps as shown in FIGS. 1 to 3 are used. As shown in FIG. 1, avolume hologram photosensitive material 1 such as a photopolymer isfirst provided as a hologram photosensitive material. Then, thecharacter or image pattern to be displayed on the photosensitivematerial 1 in a superposed fashion, for instance, a character patternplate 2 comprising an opaque “ABC” pattern portion 2 a and itstransparent peripheral portion is placed on the photosensitive material1, which is then irradiated with light 3 such as ultraviolet light fromthe character pattern plate 2 side. With the volume hologramphotosensitive material 1 irradiated with light 3 through the characterpattern plate 2, an area of the photosensitive material 1 other than aportion (1 a in FIG. 3) corresponding to the pattern portion 2 a thereofremains inert while only the portion 1 a corresponding to the patternportion 2 a provides an activated area.

As shown in FIG. 2, on the other hand, a separately provided volumehologram photosensitive material 5 is superposed on a scatter plate 4such as a ground or opal glass plate. Then, green (G) reference light 6g for instance is incident at a given angle θ of incidence on the volumehologram photosensitive material 5 and, at the same time, greenillumination light 7 g is incident on the back surface of the scatterplate 4, so that object light transmitted and scattered through thescatter plate 4 and the reference light 6 g interfere in the volumehologram photosensitive material 5. A reflection type hologram scatterplate 5′ (FIG. 3) is thus prepared.

Then, as shown in FIG. 3, the volume hologram photosensitive material 1,whose portion other than the character pattern-corresponding portion 1 aremains inert as shown in FIG. 1, is superposed on the thus preparedreflection type hologram scatter plate 5′. As the volume hologramphotosensitive material 1 is irradiated at a given angle of incidencewith illumination light 8 g having the same wavelength as the referencelight 6 g used to make the reflection type hologram scatter plate 5′,the illumination light 8 g transmits through the volume hologramphotosensitive material 1 and strikes on the reflection type hologramscatter plate 5′ to diffract scattered light 9 g in the direction ofreflection. The scattered light 9 g and incident light 8 g interfere inthe activated character pattern-corresponding portion 1 a of the volumehologram photosensitive material 1, so that a reflective, scatteringhologram can be recorded in the character pattern-corresponding portion1 a.

The thus recorded character hologram 1′ is a reflection type hologramwhich diffracts green scattered light 11 g from only a portion 1′acorresponding to the pattern portion 2 a of the character pattern plate2 in the direction of reflection upon illuminated at around an angle ofincidence θ with white light 10 w having a green wavelength. In thisembodiment, a hologram for reconstructing the pattern portion 1′a in theair is reproduced from this hologram 1 to make the character hologramplate 41′. To this end, a separately provided volume hologramphotosensitive material 41 is located away from this intermediatehologram 1′. The intermediate hologram 1′ is irradiated at an angle ofincidence θ with the above green illumination light 42 g via the volumehologram photosensitive material 41, so that scattered light 11 gdiffracted from the intermediate hologram 1′ in the direction ofreflection and the illumination light 42 g interfere in the volumehologram photosensitive material 41 to make the character hologram plate41′ (FIG. 10) in the form of a reflection type hologram. It is notedthat in the arrangement of FIG. 9, the distance between the intermediatehologram 1′ and the volume hologram photosensitive material 41 isshorter than the distance between the three-dimensional object O and thevolume hologram photosensitive material 21 in the arrangement of FIG. 5.

On the other hand, the subject hologram plate 21′ is prepared as in thefirst embodiment of the present invention. As shown in FIG. 5, a volumehologram photosensitive material 21 is located away from athree-dimensional subject O such as a three-dimensional model. In thiscase, a volume hologram photosensitive material having sensitivity withrespect to three colors, red, green and blue and capable of multiplexhologram recording is used as the volume hologram photosensitivematerial 21. However, it is acceptable to use a volume hologramphotosensitive material of three-layer construction whereinphotosensitive layers sensitive to red, green and blue, respectively,are laminated one upon another. Alternatively, it is acceptable tosuperpose separately exposed color photosensitive layers.

In such a setting, red light, green light and blue light in the form ofillumination light 22 rgb are allowed to strike at an angle of incidenceθ on the volume hologram photosensitive material 21 side at the sametime or in arbitrary order. Then, the illumination light 22 rgbtransmits through the volume hologram photosensitive material 21 andenters the three-dimensional subject O, from which scattered light 23rgb is produced in the direction of reflection. The scattered light 23rgb and illumination light 22 rgb interfere in the volume hologramphotosensitive material 21, so that the reflection type hologram 21′ ofthe three-dimensional subject O can be recorded in full color (see FIG.10). This reflection type hologram 21′ is used as the subject hologramplate 21′.

The thus obtained subject hologram plate 21′ (FIG. 5) and characterhologram plate 41′ (FIG. 9) are superposed one upon another with orwithout a slight distance between them. In view of the order ofsuperposition, it is preferable that the character hologram plate 41′ islocated on the side of incidence of the illumination light 45 rgb, asshown in FIG. 10, because characters 47 g (FIG. 11) corresponding to thepattern portion 2 a of the character pattern plate 2 to be finallyreconstructed are brighter.

By superposing the character hologram plate 41′ on the subject hologramplate 21′ in this way, a hologram plate 43 is obtained. Another volumehologram photosensitive material 44 is then located in the vicinity ofthe three-dimensional subject O used to record the subject hologramplate 21′. In this condition, red light, green light and blue light inthe form of illumination light 45 rgb strike simultaneously or inarbitrary order on the volume hologram photosensitive material 44 sidefrom the opposite direction to the direction of incidence of theillumination light 22 rgb used to make the subject hologram plate 21′.Then, the illumination light 45 rgb transmits through the volumehologram photosensitive material 44 and enters the character hologramplate 41′, so that the image 1″a of the plane characters “ABC”corresponding to the pattern 1′a of the intermediate hologram 1′ at thetime of recording the character hologram plate 41′ is reproduced.Further, the illumination light 45 rgb enters the subject hologram plate21′, where it is diffracted in the direction of reflection toreconstruct the real image O′ of the recorded three-dimensional subjectO in the vicinity of the surface of volume hologram photosensitivematerial 44. Regarding the position relation of the image of 1″a of thecharacters to the real image O′, the distance between the intermediatehologram 1′ and the volume hologram photosensitive material 41 when thecharacter hologram plate 41′ is made is shorter than the distancebetween the three-dimensional subject O and the volume hologramphotosensitive material 21 when the subject hologram plate 21′ is made.As shown in FIG. 10, accordingly, the image 1″a of the characters isformed at a position nearer to the hologram plate 43 side than to thereal image O′, i.e., in front of the real image O′ of thethree-dimensional subject O.

The diffracted light from the hologram plate 43 for reproducing theimage 1″a of the characters and the real image O′ and the illuminationlight 45 rgb interfere in the volume hologram photosensitive material44, so that the multiplexed image of the three-dimensional subject O andthe pattern portion 1′a of the intermediate hologram 1′ is recorded inthe volume hologram photosensitive material 44. Thus, the image 1″a ofthe character “ABC” pattern 1′a of the character hologram plate 1′ andthe image O′ of the three-dimensional subject O are recorded as areflection type hologram in the volume hologram photosensitive material44 while they remain positioned as shown in FIG. 10.

In this way, a color hologram display 44′ is recorded such that thepattern 47 g of the characters, e.g., “ABC” can be reconstructed in theforeground of the hologram reproduced image O″ of the three-dimensionalsubject O in a spatially multiplexed manner. As shown in FIG. 11, whiteillumination light 46 w is then allowed to enter the color hologramdisplay 44′ from the opposite direction to the direction of incidence ofthe illumination light 45 rgb used to record the display, whereupon thediffracted light reproduces the color image O″ of the three-dimensionalsubject O in the vicinity of the surface of the color hologram display44′ and, in front of the image O″, reconstructs the green, planecharacter “ABC” image 47 g corresponding to the pattern portion 1′a ofthe intermediate hologram 1′. When the observer views them through hiseyes E, he can see the plane, green image 47 g of the characters “ABC”just in front of the color image O″ of the three-dimensional subject Oas if they were superposed one upon another. However, it is noted thatthis embodiment is characterized in that the shadow of the image 47 gcannot be seen in every perspective.

While the color hologram display of the present invention has beendescribed with reference to how to fabricate the same, it is understoodthat the present invention is not limited thereto and so manymodifications may be made. It is also understood that the subjecthologram plate 21′ is not limited to a hologram recorded in such asetting as shown in FIG. 5; holograms, etc. recorded by two-beaminterference may be used. To keep the distances between the subjecthologram plate 21′, character hologram plate 1′ and volume hologramphotosensitive material 27 at certain values in the setting of FIG. 5,it is desired that hologram recording be carried out while a glass layerhaving a given thickness is inserted between adjacent members. To reducethe amount of blurring of the character image 29 g of FIG. 7 while it isilluminated with white light, it is desired that, in the setting of FIG.6, the character hologram plate 1′ be as close to the volume hologramphotosensitive material 27 as possible. A color hologram display mayalso be holographically reproduced from the color hologram display 27′fabricated as mentioned above while another volume hologramphotosensitive material is placed thereon with or without a givendistance between them. In the setting of FIG. 9, if the distance betweenthe intermediate hologram 1′ and the volume hologram photosensitivematerial 41 is longer than the distance between three-dimensionalsubject O and the volume hologram photosensitive material 21 in thesetting of FIG. 5, the image 1″a of the characters can then bereconstructed while superposed on the background of the reconstructedimage O′ of the subject.

According to the color hologram display fabrication process of thepresent invention as can be understood from the foregoing, the colorpattern of plane characters, images or the like and the color image of athree-dimensional subject can be reconstructably recorded withoutcrosstalk and unnecessary interference fringes, while they are spatiallysuperposed one upon another. It is thus possible to obtain a colorhologram display which enables a bright color subject image and ablur-free, bright color pattern having visibility to be displayed at thesame time, and is of great versatility as well. According to the presentinvention, even when a color pattern of characters, images, etc. isreconstructably incorporated in the hologram for reconstructing thecolor image of a three-dimensional subject, a bright subject image canbe obtained with the same efficiency as that of a pattern-free hologram.

1. A process of fabricating a color hologram display, comprisingrecording a color three-dimensional subject image and a color pattern ofplane characters or images as hologram images by exposing a subjecthologram plate for forming the color three-dimensional subject image anda character hologram plate for reconstructing the color pattern of planecharacters or images, where the two plates are separately made, saidsubject hologram plate and said character hologram plate are spatiallypositioned with a given space located there between, and diffractedlights from said subject hologram plate and said character hologramplate are simultaneously entered in a same photosensitive material torecord interference patterns for the images and reconstructed pattern ofsaid subject and character hologram plates, with exposing light, ashologram images.
 2. The color hologram display fabrication processaccording to claim 1, wherein an area of a hologram photosensitivematerial other than a portion thereof corresponding to said colorpattern of plane characters or images of the character hologram plate isdeactivated by photosensitization, and a reflection type hologram of ascatter plate is then recorded in said portion of said hologramphotosensitive material to make said color hologram display.
 3. Thecolor hologram display fabrication process according to claim 2, whereinsaid subject hologram plate is recorded in three colors, red, green andblue and said character hologram plate is recorded in any one of red,green and blue.
 4. The color hologram display fabrication processaccording to claim 3, wherein said character hologram plate is recordedin green.
 5. The color hologram display fabrication process according toclaim 1, wherein said color three-dimensional subject image is recordedin a subject hologram plate, said subject hologram plate is recorded inthree colors, red, green and blue and said color pattern of planecharacters or images is recorded in a character plate, said characterhologram plate is recorded in any one of red, green and blue.
 6. Thecolor hologram display fabrication process according to claim 5, whereinsaid character hologram plate is recorded in green.
 7. A process offabricating a color hologram display as recited in claim 1, comprisingthe steps of employing a subject hologram plate for forming a colorthree-dimensional subject image and a character hologram plate forreconstructing a color pattern image of plane characters or images,wherein said subject hologram plate and said character hologram plateare separately made, superposing said subject hologram plate and saidcharacter hologram plate one upon another, and providing diffractedlight from said subject hologram plate and said character hologram plateto simultaneously enter in the same photosensitive material to recordsaid color three-dimensional subject image and said color pattern imageof plane characters or images as hologram images.
 8. The color hologramdisplay fabrication process according to claim 1, wherein said subjecthologram plate is recorded in three colors, red, green and blue and saidcharacter hologram plate is recorded in any one of red, green and blue.9. The color hologram display fabrication process according to claim 8,wherein said character hologram plate is recorded in green.
 10. Aprocess of fabricating a color hologram display, comprising recording acolor three-dimensional subject image and a color pattern of planecharacters or images as hologram images by exposing a character hologramplate for reconstructing said color pattern of plane characters orimages, said character hologram plate is located in front of a colorthree-dimensional subject, and diffracted light from said characterhologram plate and scattered light from said color three-dimensionalsubject are simultaneously entered in the same photosensitive materialto record interference patterns for the subject image and reconstructedpattern of said character hologram plates, with exposing light, ashologram images.
 11. A color hologram display comprising a combinedreflection type hologram and volume type hologram, said volume typehologram being of single layer or multilayer photosensitive layerconstruction, wherein a color pattern of plane characters or images anda color three-dimensional subject image are reconstructably recordedtherein while spatially superposed one upon another, wherein any shadowof said color pattern of plane characters or images is unrecorded,fabricated by the process of claim
 10. 12. A hologram plate used tofabricate a color hologram display, comprising a photosensitivematerial, a color three-dimensional subject image and a color patternimage of plane characters or images, wherein a subject hologram platefor forming the color three-dimensional subject image and a characterhologram plate for reconstructing the color pattern image of planecharacters or images are separately made, said subject hologram plateand said character hologram plate are positioned with a given spacelocated therebetween, and diffracted light from said subject hologramplate and said character hologram plate is simultaneously entered insaid photosensitive material to record said color three-dimensionalsubject image and said color pattern image of plane characters or imagesas hologram images.
 13. The hologram plate according to claim 12,wherein an angle of incidence of light employed to produce saiddiffracted light from said subject hologram plate and said characterhologram plate is equal.
 14. A hologram plate used to fabricate a colorhologram display, comprising a photosensitive material, a colorthree-dimensional subject image and a color pattern image of planecharacters or images, wherein a subject hologram plate for forming thecolor three-dimensional subject image and a character hologram plate forreconstructing the color pattern image of plane characters or images areseparately made, said subject hologram plate and said character hologramplate are superposed one upon another, and diffracted light from saidsubject hologram plate and said character hologram plate issimultaneously entered in said photosensitive material to record saidcolor three-dimensional subject image and said color pattern image ofplane characters or images as hologram images.
 15. The hologram plateaccording to claim 14, wherein an angle of incidence of light employedto produce said diffracted light from said subject hologram plate andsaid character hologram plate is equal.